1. Field of the Invention
The disclosure relates to the field of vacuum cleaners. More specifically, the disclosure relates to vacuum cleaners having removable filters.
2. Description of the Related Art
Wet and dry vacuum cleaners are equipped with special structures to allow selective suctioning of water or air. A suction system with a motor creates the vacuum and is mounted in a lid that is removably attached to a collection drum for receiving the vacuumed materials. A portion of the lid extends downward into the drum where a cylindrical filter support assembly, referenced herein as a “cage,” is mounted thereto. A filter is mounted to the cage, where the cage and filter cover a vacuum intake to the suction assembly in the lid. The suction system suctions air from the drum which draws external air or water through a hose into the drum. Remaining material, mainly air, then flows radially inward through the filter to remove particles of debris, continues through the cage through a motorized suction impeller in the lid, and then is exhausted from the vacuum cleaner.
For manufacturing and structural integrity, a typical cage is formed from a set of horizontal concentric members as “bands” joined with upright longitudinal members. Air flow can pass through open spaces formed between the concentric bands and longitudinal members. The cage supports the filter on the cage outer periphery.
While suctioning water, the suction impeller and motor can be damaged if the water level in the drum rises to a height that the water directly contacts the impeller and creates additional stress on the spinning impeller and motor. As a safety feature to such occurrences, a float is commonly installed in the cage that will float at or above the liquid level. The float historically has been a ball float and more recently has been a cylindrical float. The float is held within the cage by the concentric bands and longitudinal members. In some designs, the float is held in alignment with the suction inlet by a guide around a portion of the float within the cage.
If the liquid level rises to a sufficient height, the float will rise and block the impeller intake to restrict the flow of liquid into the impeller. When the liquid level decreases, the float lowers and the air above the liquid level can flow into the impeller.
As motor efficiencies have increased, the amount of suction power has increased. On some high capacity wet and dry vacuums, the air flow is so great that the air flow can lift the float and unintentionally block the impeller inlet even without a high water level. Thus, the cage has been modified to create a restricted flow section of the cage.
FIG. 1 is a perspective schematic view of a typical prior art concentric filter cage having a restricted flow section installed in a wet and dry vacuum cleaner. The cage 2 has a series of concentric members 3 coupled with longitudinal members 4. A filter 5 is inserted over the cage 2. A restricted flow section 6 is created in a lower portion of the cage 2 where a float 7 would generally rest by forming a bottom-closed, open-top, float container 8 in the cage. Thus, airflow is blocked in the lower portions of the cage from the float, so that the float will only rise when water level rises and overflows into the open top of the float container 8. The air flow is primarily restricted to flow through the open flow zone 9 into the cage and then the impeller. Such restrictions can affect the performance in two ways. Only a portion of the filter is efficiently utilized. Further, the volume of air flow is restricted due to less than the full depth of the cage being available for air flow radially inward.
Therefore, there remains a need for an improved cage design and system for a filter in a vacuum cleaner.